Glossary

access log

A log file that contains information about the HTTP requests sent to Oracle Web Cache for a Web site. The access log has a file name of access_log and is stored by default in the following directories:

An origin server that manages data for a Web site, controls access to that data, and responds to clients requests. The application on the Web server interfaces with the database and performs the job requested by the Web server.

An instance of Oracle Web Cache configured with other instances of Oracle Web Cache to operate as one logical cache. The cache cluster members communicate with one another to request cacheable content that is cached by another cache cluster member and to detect when a cache cluster member fails.

An HTTP or HTTPS request that can be served from objects stored in the Oracle Web Cache cache without going to the origin server.

cache miss

An HTTP or HTTPS request that cannot be served from the cache and must be forwarded to an origin server.

cache server process

An Oracle Web Cache process that manages the cache by providing connection management and request processing.

capacity

For origin servers, the maximum number of concurrent connections that the origin server can accept.

For cache clusters, the absolute capacity for the number of concurrent incoming connections to this cache cluster member from all other cache cluster members, and the relative capacity of the cache cluster member.

category cookie

A cookie that enables the multiple version of the same page to served to different categories of users.

A packet of state information sent by an origin server to a Web browser during an HTTP request. During subsequent HTTP requests, the cookie is passed back to the origin server, enabling the origin server to remember the state of the last transaction.

A demilitarized zone (DMZ) or perimeter network is a network area (a subnetwork) that sits between an organization's internal network and an external network, usually the Internet. The point of a DMZ is that connections from the internal and the external network to the DMZ are permitted, whereas connections from the DMZ are only permitted to the external network; hosts in the DMZ may not connect to the internal network. This allows the DMZ's hosts to provide services to both the internal and external network while protecting the internal network in case intruders compromise a host in the DMZ.

A system for naming computers and network services that is organized into a hierarchy of domains. DNS is used in TCP/IP networks to locate computers through user-friendly names. DNS resolves a friendly name into an IP address, which is understood by computers.

A function that marks objects as invalid after a certain amount of time in the cache. When objects are marked as invalid and a client requests them, they are either immediately removed and refreshed or refreshed based on when the origin server can refresh them.

Extended Log Format (XLF)

An improved format for HTTP server logins since it is extensible, permitting a wider range of data to be captured. XLF enables you to configure the logger to generate different statistics of HTTP requests such as the IP address of clients, methods of the HTTP requests and response headers such as user agent and accept.

Extensible Markup Language (XML)

A language that offers a flexible way to create common information formats. XML is used for invalidation messages and responses.

farm

A collection of components managed by Fusion Middleware Control. It can contain zero or one managed server domains and the Oracle Fusion Middleware system components that are installed, configured, and running on the domain.

failover

When an origin server fails, Oracle Web Cache automatically distributes the load over the remaining origin servers and polls the failed origin server for its current up/down status until it is back online. In a cache cluster environment, Oracle Web Cache transfers ownership of the content of the failing member to the remaining cluster members.

failure detection

In a cache cluster environment, Oracle Web Cache detects when a cache cluster member is unavailable.

GET method

An HTTP request method used for simple requests for Web pages. A GET method is made up of a URL. Requests for pages that use the GET method are typically cached.

GET method with query string

An HTTP request method made up of a URL and a query string containing parameters and values. An example of an HTTP GET with query string follows.

http://www.myserver.com/setup/config/navframe?frame=default

This request executes a script named navframe in the /setup/config directory of the www.myserver.com server and passes the script a value of default for the frame variable.

Note:

You should not cache pages with GET with query strings forms that make changes to the origin server or database. You should only cache pages that use GET with query strings if they are used in searches.

Hypertext Transfer Protocol. A protocol that provides the language that enables browsers and the origin server to communicate.

HTTP request header

A header that enables Web browsers to pass additional information about the request and about itself to the origin server.

HTTP request method

A method included in the HTTP request that specifies the purpose of the client's request. HTTP supports many methods, but the ones that concern caching are GET, GET with query string, and POST methods.

An Oracle Web Cache function that marks objects as invalid. When objects are marked as invalid and a client requests them, they are removed and then refreshed with new content from the origin server. Invalidation keeps the Oracle Web Cache cache consistent with the content on the origin servers.

invalidation coordinator

In a cache cluster environment, Oracle Web Cache propagates invalidation messages to other cache cluster members. It sends the invalidation messages to one cache cluster member who acts as the coordinator. The coordinator propagates the invalidation messages to the other cluster members.

IP address

Used to identify a node on a network. Each computer on the network is assigned a unique IP address, which is made up of the network ID, and a unique host ID. This address is typically represented in dotted-decimal notation, with the decimal value of each octet separated by a period, for example 144.45.9.22.

latency

Networking round-trip time.

load balancing

A feature in which HTTP requests are distributed among origin servers so that no single server is overloaded.

A mechanism for balancing the load of incoming requests. This mechanism is typically a hardware load balancer in the form of a network switch, such asLayer 7 (L7) switch. A hardware load balancer is typically positioned in front of the Oracle Web Cache server. Oracle Web Cache can act as a software load balancer for environments where a hardware load balancer is not available.

on-demand content

In a cache cluster environment, on-demand content consists of popular objects that are stored in the cache of each cluster member.

Open Systems Interconnection (OSI)

A model of network architecture developed by ISO as a framework for international standards in heterogeneous computer network architecture.

The OSI architecture is split among seven layers, from lowest to highest:

1. Physical layer

2. Data link layer

3. Network layer

4. Transport layer

5. Session layer

6. Presentation layer

7. Application layer

Each layer uses the layer immediately following it and provides a service to the preceding layer.

Oracle Enterprise Manager

A tool for administering Oracle Application Server. It is a complete management solution for administering, configuring, and monitoring the application server and its components. Using it, you can:

View the overall status of Oracle Web Cache

View performance metrics

Oracle Web Cache Manager

A tool that combines configuration abilities with component control to provide an integrated environment for configuring and managing Oracle Web Cache.

In a cache cluster environment, content that is owned by a particular cache cluster member. Oracle Web Cache distributes the cached content among the cache cluster members. In effect, it assigns content to be owned by a particular cache cluster member.

partial page caching

A feature that enables Oracle Web Cache to independently cache and manage fragments of HTML objects. A template page is configured with Edge Side Includes (ESI) markup tags that tell Oracle Web Cache to fetch and include the HTML fragments. The fragments themselves are HTML files containing discrete text or other objects.

performance assurance heuristics

Heuristics that enable Oracle Web Cache to assign a queue order to objects. These heuristics determine which objects can be served stale and which objects must be retrieve immediately. While objects with a higher priority are retrieved first, objects with a lower priority are retrieved at a later time.

The queue order of objects is based on the popularity of objects and the validity of objects assigned during invalidation. If the current load and capacity of the origin server is not exceeded, then the most popular and least valid objects are refreshed first.

personalized attribute

Pages that contain personalized attributes, such as personalized greetings like "Hello, Name," icons, addresses, or shopping cart snippets, on an otherwise generic page. You can configure Oracle Web Cache to substitute values for personalized attributes based on the information contained within a cookie or an embedded URL parameter.

popularity

The number of requests for an object since entering the cache and the number of recent requests for the object.

POST body parameter

Parameter information embedded in the POST body of objects.

POST method

An HTTP request method used for requests that modify the contents of the data store on the origin server, such as posting a message to a mailing list, submitting forms for registration purposes, or adding entries to the database.

Note:

You should not cache pages with POST forms that make changes to the origin server or database. You should only cache pages that use POST forms if they are used in searches.

proxy server

An origin server that substitutes for the real server, forwarding client connection requests to the real server or to other proxy servers. Proxy servers provide access control, data and system security, monitoring, and caching.

provider

Set of content—content areas, pages, applications, even data from outside sources—brought in one central location and accessed through a common interface, called a page.

provider cache

In an ESI cache hierarchy, an Oracle Web Cache server that locally caches content for a provider site. A subscriber cache then contacts the provider caches for assembly of HTML fragments. When content becomes invalid, the provider cache propagates the invalidation request to the subscriber cache to ensure consistency.

In a distributed cache hierarchy, an Oracle Web Cache server that caches content from a central cache to serve local requests. When an invalidation request is sent to the central cache, the central cache propagates the request to the remote cache, ensuring consistent content.

reverse proxy

A server that appears to be the content server to clients but internally retrieves its objects from other back-end origin servers as a proxy. A reverse proxy acts a gateway to the origin servers. It relays requests from outside the firewall to origin servers behind the firewall, and delivers retrieved content back to the client.

round robin

A method of managing server congestion by distributing connection loads across multiple servers. Round robin works on a rotating basis in that the first origin server in the list of configured servers receives the request, then the second origin server receives the second request, and so on.

Secure Sockets Layer (SSL)

A protocol developed by Netscape Corporation. SSL is an industry-accepted standard for network transport layer security. SSL provides authentication, encryption, and data integrity, in a public key infrastructure (PKI). By supporting SSL, Oracle Web Cache can cache pages for HTTPS protocol requests.

selectors

Oracle Web Cache uses selectors to filter through the caching rules to locate the appropriate rule for the request. Cacheability can be evaluated against the following selectors:

HTML hyperlink tags, such as <A HREF=...>, that contain embedded session information to distinguish users. You can configure Oracle Web Cache to substitute the values of session parameters in HTML hyperlink tags with the session information contained within a session cookie or an embedded URL parameter.

subscriber cache

In an ESI cache hierarchy, an Oracle Web Cache server that assembles ESI content by contacting a provider cache for the template's HTML fragments. The HTML fragments are then assembled. When provider site content becomes invalid, the provider site propagates the invalidation request to the subscriber cache to ensure consistency.

A standard for specifying the location and route to a file on the Internet. URLs are used by browsers to navigate the World Wide Web and consist of a protocol, domain name, directory path, and the file name. For example, http://www.oracle.com/technology/index.html specifies the location and path a browser travels to find the main page of the Oracle Technology Network site on the World Wide Web.

A site hosted by Oracle Web Cache. Browsers can request cached content from these sites through Oracle Web Cache. In addition to caching content, Oracle Web Cache can also assemble ESI fragments from these sites.

wallet

A transparent database used to manage authentication data such as keys, certificates, and trusted certificates needed by SSL. A wallet has an X.509 version 3 certificate, private key, and list of trusted certificates.

A utility used to start, stop, and restart the admin server process, the cache server process, and the auto-restart process, if Oracle Web Cache is running in a standalone environment (that is, you installed Oracle Web Cache from a kit that included only this product; you did not install Oracle Web Cache as part of an Oracle Application Server installation).